Bone screw for providing dynamic tension

Abstract

A bone screw including a head portion, an intermediate portion, and a threaded portion. The intermediate portion further includes a wave-type spring formed therein. In one exemplary embodiment, the wave-type spring is formed to have a lattice structure. In one exemplary embodiment, the wave-type spring of the intermediate portion is formed by laser cutting. By providing a wave-type spring in the intermediate portion of the bone screw of the present invention, the bone screw provides dynamic tension to maintain a bone plate or other orthopedic device in its desired position substantially adjacent a bone.

Description

BACKGROUND[0001]1. Field of the Invention[0002]The present invention relates to orthopedic devices and, particularly, to bone screws for use with orthopedic devices.[0003]2. Description of the Related Art[0004]Orthopedic devices, such as bone plates, may be used to maintain opposing portions of fractured bones substantially stationary relative to one another. For example, a bone plate may be formed as an elongate body having apertures extending therethrough and may be positioned to extend across the fracture line in a bone. Once positioned, bone screws may be inserted through the apertures to secure the bone plate to the fragments of the bone and maintain the opposing portions of the fractured bone in compression against one another.[0005]Once inserted, the tension on the bone screw is initially large enough to maintain the opposing portions of the fractured bone and / or the bone plate in compression against one another. However, the opposing portions of the fracture bone may also un...

AI Technical Summary

Benefits of technology

[0009]In one exemplary embodiment, the wave-type spring of the intermediate portion of the bone screw is formed by a plurality of arms connected to one another at at least two discrete locations, which define junction points therebetween. As a result of the connection between the plurality of arms forming the wave-type spring, the bone screw of the present invention allows for a greater torque to be applied to the bone screw of the present invention without deforming the same.

[0010]In another exemplary embodiment, the bone screw of the present invention may include an internal bore and an alignment pin configured to travel within the internal bore. Thus, as the length of the bone screw is increased or decreased, the alignment pin travels along the internal bore and may contact the wall defining the internal bore. This contact between the alignment pin and the wall defining the internal bore provides additional axial rigidity to the bone screw. In another exemplary embodiment, the bone screw of the present invention may include a sleeve extending around at least a portion of the intermediate portion of the bone screw. The use of a sleeve also provides additional axial rigidity to the bone screw.

Problems solved by technology

As a result, the springs of these bone screws substantially decrease the axial rigidity of the bone screws along the length of the springs.

More importantly, the amount of torque that can be applied to known dynamic tension bone screws is substantially limited.

Specifically, if these bone screws are over-torqued, the coils of the springs formed therein may be displaced from their desired position, e.g., may expand outwardly, and the bone screw may become unusable.

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